: Separate Image Differences on almost identical images I am usually proficient in Photoshop but this one is really stumping me. I have two almost identical images and I need to separate the differences

@Debbie163

My aproach would be:

1) Copy one image and paste it as a new layer over the other image.

2) Set the Layer mode to Diference.

3) Flatten the image.

4) Invert the image (negative).

5) Clean it.

This technique can be used not only in this case but also with photos.

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@Debbie163

It's not a perfect technique, some pixels will be destroyed, it will also destroy some anti-aliasing, and you'll also lose that small shadow around the dots. But it can be easier to isolate your dots this way and not drag some of the map background with the dots.

There's many ways to do this, including selecting the red color and copy/pasting them on a new layer.



Here is another technique that I would use for this (I personally don't like using the wand tool):

1) Set your color mode to CMYK

2) Open the channel window; delete everything in the Cyan and Yellow channel

3) On the magenta channel, open your "levels" and use the white color picker on the midtones until all the pixels from the names disappear.



An alternative: Boost the curve of the magenta instead, to make the lighter part white



4) Do the same with the black channel, but make the black around the circle to 100% using the black color picker too.



5) You will need to delete manually some stuff like the word "United State" and some cities, but it's quickly done with the rectangle selection tool. They should be only on your black channel at this point.



6) Boost back the magenta color to red using hue/saturation, selective color or anything you prefer for this.

7) You'll end up with a white background. You can delete the white or use a multiply blending on your top layer.



Here is the final result with the layer with the dots using "multiply" but no shadow.



Here is the final result with the transparent background and a drop shadow:


If you use a small drop shadow, it will smooth a bit the edges of
your circles.
You can also add a 1pt black stroke; I used one at 75% transparency
to simulate the anti-aliasing and not make the edges too dark.







Note: The screenshots for the "steps" are zoomed in; the quality looks
a bit better at 100%.

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